Looking for some advice, what's going to make a motor easier to start between 40 and 50 degrees, SAE 30 weight VR1 or 20w50? Both are not synthetic. Not sure how to read the product sheets, seems logically like the 20w50 but viscosity is lower on the SAE 30.
Valvoline VR1 cold starting viscosity of SAE 30 and 20w50?
- Thread starter ragtophardtop
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Use the Widman calculator.
Just to make sure I understand this, I put the values from 20-50 in correctly and the 30 is labeled as 10w40 on the graph. It looks like 20w50 is twice as thick at those temps than this SAE 30, correct?
https://www.widman.biz/English/Calculators/Graph.html
https://www.widman.biz/English/Calculators/Graph.html
It's double at basically any temperature, except when you get well below 0°C but the Widman calculator doesn't work down there, it can't deal with the viscosity improvers in the 20W-50.
ok, so that exercise didn't work. Back to square 1. Which one would be easier to start at 40 degrees, and how much easier?
It works fine for the temperatures you’re asking about. You’re seeing the difference between a 30-grade and a 50-grade. The fact that the 50-grade is a multi is relatively insignificant at the temperature being discussed.
Are you actually having issues starting at 40 degrees? If you are, that’s not a problem with the oil. At that temperature it’s a problem with the battery, the starter, or the engine. You should be able to start nearly every engine at that temperature even if it’s a 70-grade oil.
It's a custom built bored and stroked antique german motor. She's very cold blooded. First thing I'm wanted to try is changing the oil, if the 30w would turn over easier I'll put that in. The 20w-50 was put in by the mechanic who said it wasn't for driving in the winter, but I've had to start and move the car a couple of times unplanned, which were more difficult on the motor than I'd like.
Do I understand, the 30 weight at 40 degrees will be less viscous than the 20w50? I understood the 30W should act about 30 at that temp, and the 20w50 should act closer to a 20w. ?
BrendanC
$100 site donor 2024
sounds like you need to work out a high torque starter rather than try and change oil viscosity. being an “antique” starter technology wasn’t great and it’s probably a direct drive starter that’s terribly inefficient. look for a way to get a more modern gear reduction starter on it. would probably recommend replacing the hot and ground wire with some good 2awg+ cable and a nice hot battery.
The 20W rating is determined by a test done at -15°C. It won't necessarily correlate to cranking performance at 5-10°C.
Also, the cold cranking test just isn't done on straight grade oils. If the SAE 30 was actually tested for cold cranking performance, it might perform like a 20W. It won't necessarily have the cold cranking performance of a 30W just because it's an SAE 30.
I'd put my money on the SAE 30 being better for cranking at those temperatures.
Yeah, what twX wrote. There's no reason they can't "secretly" make the 30 weight have an unadvertised winter rating. People "know" a monograde is more shear stable than a multigrade but the base oils now are so good you could have a 15w30. But marketing won't allow it because people will think it's not as "tough."
There are things like pour point depressants that can cause things to go non-linear and off Widman's scale, but IDK if either oil really needs or would get them.
My 91 F150 had a "dragging" starter that seemed for all the world like thick oil or a bum battery. Turns out it was the same direct drive motor style they had in 1965, and on its last leg. I put a gear reduction unit in that was intended for a 1995 and it works super now. I suspect your starter bolt pattern is not incredibly unique-- your German engine engineers probably picked an off-the-shelf part and made the bell housing to fit. Or you could see if your starter motor needs a rebuild or refresh, just polishing the copper parts inside and de-gunking.
There are things like pour point depressants that can cause things to go non-linear and off Widman's scale, but IDK if either oil really needs or would get them.
My 91 F150 had a "dragging" starter that seemed for all the world like thick oil or a bum battery. Turns out it was the same direct drive motor style they had in 1965, and on its last leg. I put a gear reduction unit in that was intended for a 1995 and it works super now. I suspect your starter bolt pattern is not incredibly unique-- your German engine engineers probably picked an off-the-shelf part and made the bell housing to fit. Or you could see if your starter motor needs a rebuild or refresh, just polishing the copper parts inside and de-gunking.
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The car is a warm weather project, I'm going to try the 30w oil first, or just heating the oil and putting it back in. I really don't intend to drive it in the cold where it would necessitate getting a new starter, or a windshield, I just need to move things around in the garage more than I expected this winter. It starts up fine in the summer, I think the cold air induces a lean condition on startup requiring more cranking than should be necessary to get it to catch, the car is built for top end.
It won't be a 15W30 with the advertised viscosity index, it's just a monograde mineral oil. If the viscosity index was higher due to PAO or ester content, it might.
If this is your primary concern then why use a monograde in the first place? Why not a Euro 5W-30 which would have sufficient HT/HS and better cranking and pumpability when cold? Why the artificial constraint of only two choices?
If you look at the original post, the car has a built flat tappet motor and these 2 oils were specified by the builder, high zinc mineral oils. The OEM rec is straight 30w.
@eljefino Dipstick tube extractor. These oils are specialized high zddp mineral oils for use in classic vehicles and race cars, so it's a bit beyond marketing.
Okay sure. Then use the 30-grade and don't start below 0F.
Several SAE papers confirmed that ZDDP above a level of 0.03 does nothing more but act in reserve as the zinc gets depleted (in ZDP formulated oils). So any modern ZDP formulated oil (around 800ppm) would work in that engine. Also, all newer SAE rated oils have always been backwards compatible. Those with no ZDP at all are supposed to work just as well (actually better) as all older formulations that are ZDP based. Hence a 1910 Rolls Royce should run and be better protected with a zincless synthetic oil - though the block seams may seep oil.
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